What is the Core?

COREman misconceptions

Why your core is soooooo important

Lets start off by getting to the “CORE” of this issue.
​When I ask close to 90% of clients I treat to tell me what the core is they can’t, and this makes it hard to understand what the core actually does.

So what exactly is the "core"

The core is a group of muscles that provide stability to the axial Skelton. 
Major muscles included are (in order of approximate depth of the body/closeness to the body’s core):

• Transversus abdominis (TvA)
• The pelvic floor muscles
• The diaphragm.
• Internal and external obliques
• Multifidus
• Erector spinae group (ESG). Sacrospinalis and the longissimus thoracis
• Rectus abdominis
• Minor core muscles include the latissimus dorsi, gluteus maximus, and trapezius (but these are also have primary roles in locomotion)

The main contributor to this stability is Transverse abdominus. Transverse abdominus is the deepest of the flat muscles of the abdominal area. It is called this due to its transverse fibre direction (transverse meaning made at right angles to the long axis of the body)

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What does Transverse Abdominus do?

Transverse Abdominus has multiple roles but its primary role is stability. If we define stability as the ability to limit displacement and maintain structural integrity. The TvA, when used correctly  (along with primarily the pelvic floor and diaphragm muscles)  provide intra-abdominal pressure which helps to provide a longitudinal force on the spine, pelvis and trunk(Figure 1.2).
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​We can assume that, core stability can be defined as the ability of the Thoraco-lumbopelvic-hip complex to prevent shear, bending and torsional forces to cause damaging or buckling such as (kyphosis, Lordosis or scoliosis) of the vertebral column and return it to equilibrium (neutral)  following perturbation (external forces).

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If you aren't sure about how to use your core please don't hesitate to contact us

What happens when we don’t use our core?

As mentioned before our core provides a longitudinal force on our entire torso. This is very important as gravity (along with the ground reaction force) also provides a longitudinal force in the opposite direction. 
Because of the TvA fibre direction it is the only muscle able to provide tension or decompression to the lumbar spine.

Multiple studies have look at the core and its relationship to injury and lower and upper body function, and have all come up with the same conclusions such as decreased core stability may predispose to injury and that appropriate training may reduce injury.

Participants with chronic LBP receiving motor control exercise had a greater improvement in recruitment of transversus abdominis (7.8%) than participants receiving general exercise (4.9% reduction) or spinal manipulative therapy (3.7% reduction). 
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There was a significant, moderate correlation between improved recruitment of transversus abdominis and a reduction in disability specific training by physical therapy in the raising of the intra-abdominal pressure as a protection for the spine might be of great benefit to patients recovering from “ slipped disc “ or operations upon the spine.

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Now for my Rant!

​Transverse Abdominus creates stability using tensegrity or biotensegrity to be precise. This is defined by Kenneth Snelson, to indicate that the integrity of the structure derived from the balance of tension members, not the compression struts.

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​In lamens terms you can use the analogy that our bodies behave like a suspension bridge (they are able to disperse  external forces such as when a large storm causes movement but not cracking), as opposed to a  house or stone arch , which is built on compression and has no movement properties.

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I am about to make some assumptions but before that I will tell you them I want to share what findings I will base them on.

What we know:
Transvere abdominus is innervated by the intercostal nerves (arising from nerve roots T7-11) and the iliohypogastric nerve and the ilioinguinal nerve (L2-4)
TvA roles are to:

• Stabilise the thorax and pelvis during dynamic movements
  • Without a stable spine (proper contraction of the TvA) the nervous system is inhibited in providing correct recruitment to peripheral muscles this will inhibit the body to perform these functions or functional activities correctly (eg. Standing, walking, running, throwing, lifting, jumping).
• Provide intraabdominal pressure
• Originates most if not all of the body’s functions
• Return the body to a position of neutral when acted upon by an external, or internal force
• Provides static core functionality to resist
  • Gravity
  • Produce movement and resist movement in all planes of motion (transverse [head to toe], sagittal [left to right], and coronal [ front to back]

 
It is common knowledge muscles can work concentrically, eccentrically and isometrically.

I am going to make an assumption here that muscles can do more than one thing at once.

• We have proven that TvA is:
  1. Active in trunk rotation (greater with contralateral rotation initially but by the time movement starts it has evened out)
  2. Active with walking (greater with heel strike)
  3. Active in breathing
  4. Active with arm movements

Our body is designed to do these things together and not independantly, However our limited ability to research multiple factors at any time is very evident in science today.

We know that Synergists act together to produce or control a movement (eg the hamstring complex and the gastrocnemius muscle act along with certain fibres of adductor magnus to produce knee flexion, inhibit anterior translation of the tibia on the femur, while maintaining knee positioning through range in the coronal, sagittal and frontal planes.

​So why shouldn’t your core be able to do all those things?

Pain is very rarely (I am going to stick my neck out here and say never) a single muscle or structure issue. However a lot of research  tends to lean towards the changes of TvA being constant while other musculature is not. 

Some more recent research suggests that pain maybe linked  to overuse of superficial muscle activation and that training of bilateral activation is an effective training stimulus to change the way the muscle is activated in function, despite the fact that this may not be the only way it is active in function. This principle of a training stimulus that does not reflect every function is true for many exercise approaches.

My Summary

​The core is a very important group of muscles its primary role is to provide tensegrity to the trunk to allow the peripherals to move off a tensed structure not compressed. Without correct  TvA is you will not be able to produce a longitudinal/decompressive  force on your spine and trunk. Compression leads to forces such as shear, bending or torsion. If these are done in a controlled manner then the elastic properties of the soft tissue will not adapt however if this is sustained creep or distortion becomes a big problem.

The actual numbers of force through the spine

Discs have a yield (point before permanent damage is done) of between 150 and 600 kgs of force. To put that into perspective  I will quote directly with lb to kg conversion in brackets)  from a study done.

“A weight of 100 pounds (45kgs) acting on the long lever is only a modest representation of what actually can be lifted by a strong man ; and to this weight should be added the weight of head and shoulders. Let the lever be only fifteen inches, but let us assume that he lifts 200 pounds (90kgs) plus fifty pounds (head, shoulders and thorax), then the pressure in the lumbo-sacral disc will be 2,000 pounds (910kgs). This calculation is based upon stationary forces. And not dynamic ones. The calculation for force is Force = mass time accereration (F= ma). This is important to realise that the acceleration and deceleration forces multiply (not adds) to the total force on the spine.
The pressures that appear during violent action according to this reasoning must be considerably higher and can only be characterised as enormous.
 
Without correct core you should not be lifting heavy or fast

PLEASE EXCERCISE WITH TRANSVERSE ABDOMINUS ACTIVATION TO DECOMPRESS YOUR SPINE AND MINIMISE INJURY RISK

Something to ponder

The Human and mammal trunk is separated  by the diaphragm. The position of the Lungs inside the thoracic cavity (outside the intraabdominal pressure) is an obvious advantage in the evolutionary process. In our situation breathing can occur even when the core is turned on and used as a support and cannot be relaxed. This means that range of flight (ability to work at an aroused level) of an animal having the lungs outside the “core” greater than that of an animal who has its lungs in the single body cavity, which can just make a spurt and then has to stop to breathe.
​Could it be that it is for this reason that the mammals have developed a diaphragm?
Why are you holding your breath when you exercise?
#alwayslearning #physiolabs #humanmovement #humanevolution #core #posture #TvA #functionalpatterns #functionalpatternsqueensland #functionalpatternsgoldcoast #lifting

​Sean Yates | Physiotherapist | Doctor of Physiotherapy | Bachelor of Exercise Science |
ASCA level 1 | AWF Level 1 coach | Functional Patterns Level 1, 2, 3 | Human Biomechanics Specialist | Dry Needling | Clinical Pilates Level 1, 2, 3 | APA sports Level 1 | Watson Headache Level 1 | IASTM - Smart Tools Instructor |